Binding of Shaker-type K⁺ channels by DLG as determined by semiquantitative yeast two-hybrid assay, based on induction of yeast reporter genes HIS3 and β-gal. HIS3 activity was measured by the percentage of colonies growing on histidine-lacking medium [+++ (>60%); ++ (30–60%); + (10–30%); − (no significant growth)], and β-gal activity by determining the time taken for colonies to turn blue in X-gal filter lift assays at room temperature [+++ (<45 min); ++ (45–90 min); + (90–240 min); − (no significant β-gal activity)].